bug#36649: 27.0.50; pure space and pdumper

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: luangruo@yahoo.com,  pipcet@gmail.com,  36649@debbugs.gnu.org,
>   monnier@iro.umontreal.ca
> Date: Sat, 02 Jul 2022 19:23:24 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > No, I'm okay with having the purespace removed from the pdumper
> > builds, if the unexec build can still use it.  AFAIU, that's the
> > "behind several ifdefs" alternative.
> 
> One reason to get rid of pure space is to get rid of all the calls to
> build_pure_c_string etc etc that litter the code, but just disabling
> pure space in pdump doesn't help us with that.  (And the reason we want
> to do that is to make the code easier to approach for people.)

Yes, I understand that this change has 2 parts: the syntactic part
(removing the calls to *pure* functions from our sources) and the part
that removes the use of purespace.  The first part will have to wait
until we remove the unexec support; the second part can either wait
till then, or we can stop using purespace in the pdumper builds now.